This invention relates to ultrasonic dental tools or instruments, and, more particularly, to ultrasonic instruments or tips which when installed on an ultrasonic handpiece and which when energized with ultrasonic energy resonate such that the when the vibrating tip is brought into working contact with tooth material, the tip will abrade the tooth material in contact with the working end of the tip such that the tooth material can be removed in a controlled fashion. Even more specifically, such ultrasonic tips are useful in carrying out a variety of dental procedures, such as tooth cleaning, and are useful in preparing the canal of a tooth during root canal and endodontic procedures. Such ultrasonic dental tips are known, as shown in U.S. Pat. Nos. 5,094,617, and 5,868,570, and International Publication No. WO 00/74586.
In performing root canals, it is important for the clinician to have visibility of the canal with the instrument in operation, particularly when performing root canals deep within root structure. Prior art ultrasonic instruments have, in the past, provided improved visibility over rotary driven instruments (e.g., burs) because the high speed rotary handpiece head driving the bur is eliminated which opens up the field of view into the canal and of the instrument. However, there is still a need for better visibility while using ultrasonic tips, particularly when the cutting tip of the instrument is deep in the canal.
In performing root canals in maxillary molars, it is important to search for, to locate, and to treat MB2 canals. Such MB2 canals are present a large percentage of the time and they often have separate portals of exit. Locating and entering such MB2 canals with conventional instruments is difficult and time consuming. When such canals are located, it is difficult to maneuver conventional instruments into such canals during treatment. Ineffective geometries of prior art ultrasonic tips have made the location of such MB canals difficult because such prior art tips had sharp tips which created clefts and ditches in the pulp chamber floor which, in many instances, had the appearance of MB canal fins when such canal was not present. If a smooth trough can be created, particularly when viewed under magnification, a distinct line may be seen to extend between the MB1 orifice in a palatal direction to the MB2 canal. However, conventional ultrasonic tips are not effective in creating such smooth troughs.
It is also important to be able to smooth pulp chamber floors without cutting past the floor. In molars it is necessary to plane through the lighter colored calcific dentin to gain access to the darker colored pulp chamber floor dentin. With conventional ultrasonic tips, ditching often occurs which obscures the pulp chamber floor anatomy.
While the above-noted prior art tips have worked well for their intended purposes, there has been a need for an ultrasonic tip that is especially adapted for cutting of dentin and enamel and which maximizes the clinician""s field of view of the operating site while using the tip to prepare for root canal procedures. There has also been a need for an ultrasonic tip that allows the practitioner to horizontally smooth pulp chambers when performing a root canal and to safely plane attached pulp stones in the canal without cutting past the stone. Still further, there has been a need for a tip that is extremely active when rendered resonant at ultrasonic frequencies for cutting apically into calcified canals and for digging around posts that may have become embedded in the canal.
Among the several objects and features of the present invention may be noted the provision of a series of ultrasonic tips for use with an ultrasonic dental handpiece which when activated may be efficiently used to eliminate clefts and ditches in the pulp chamber floor, for cutting and refinement of line angles, for smoothing the walls of the canal, and for cutting MB troughs when performing root canal procedures;
The provision of such tips which permits the practitioner to readily smooth pulp chamber floors and to safely plane attached pulp stones without cutting past them;
The provision of such tips which are highly active when energized and which enable the practitioner to readily cut apically into calcified canals and around posts;
The provision of such tips that provide micro-abrasion cutting efficiency when energized;
The provision of such tips which have geometries that aid visibility of the practitioner during use in the tooth;
The provision of a tip which smoothes the cutting action and minimizes ledging and perforations;
The provision of such tips which facilitates the location of and access to MB2 canals in molars;
The provision of such tips which improves the field of view of the operating site and which optimizes the ability of the practitioner to use loupes and microscopes during root canal surgery, particularly when the tip is deep in the canal; and
The provision of such tips which are shaped so that they are comfortable for the practitioner to use, which are shaped so that the tip is in the proper position to perform its intended function as the clinician holds the handpiece in the conventional manner, which is readily activated when the handpiece is energized, which has a long service life, which readily cuts through dental materials, and which is easily maneuvered and controllable in the operating site.
A dental instrument of the present invention is for use with an ultrasonic dental handpiece for performing endodontic procedures. The handpiece has an ultrasonic transducer therein and an output stud or chuck which is operatively coupled to the transducer such that when the transducer is rendered resonant, the output chuck is vibrated in axial direction. The instrument further has a hub adapted to be operatively coupled (e.g., threaded) to the output chuck. A first shank portion extends from the hub in a generally axial direction and tip portion of the shank extends from the first portion. The shank has a bend therein (sometimes referred to as a contra angle) between the first portion and the tip portion ranging between about 90xc2x0 and about 140xc2x0. The tip portion has a generally bulbous (enlarged) free end with the latter having a cross sectional area (or diameter) of about one-and-one-half times to about twice (or even larger) the cross sectional area of the tip portion proximate the bulbous free end.
Further, the bulbous free end has an abrasive coating thereon (preferably on its end face) so that upon activation of the instrument by the transducer, the tip portion and the bulbous free end vibrate in a plane.
Stated differently, the dental instrument of the present invention has a hub adapted to be operatively coupled to the output chuck and a shank portion extending from the hub. The shank has a first portion that extends in a generally axial direction from the hub and tip portion extends from the first portion. The shank has a bend therein between the first portion and the tip portion ranging between about 90xc2x0 and about 140xc2x0. The tip portion has a free distal end with the latter having a radius ranging between about 0.25 mm. and about 1.00 mm. such that when the tip is rendered resonant by the transducer and is brought into operating engagement with a tooth, the radiused distal end will remove dental material from the tooth substantially without scratching the tooth thereby facilitating visual identification of the canal in the tooth.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.